As most players will surely agree, one of the things that make TDM great are its visual capabilities, which come from idTech 4 having been so well designed. As I've been playing more with rendering and game engines during the last period, I realized this is something worth bringing up in the graphics department. I dare suggest it since frankly, TDM has some of the best graphics in the world of open-source games today... the idea of adding a common effect that would rocket its visual quality even higher sounds acceptable enough to post about.
Typically there are two light occlusion effects, though I can imagine them combined in one by a smart renderer: Ambient Occlusion to simulate darkening in tight spaces, and Global Illumination to simulate light reflecting off surfaces. They're often costly to calculate for realtime lights, but there are engines that do it right... Tesseract (FPS based on Cube 2) offers a great example of doing FPS-cheap GI! A more serious problem specific to TDM is that this would affect the brightness of areas, and in turn the gameplay on existing maps... it would need to be an user option for this reason.
I'm mostly curious on the opinions of the devs; Could at least SSAO be considered at some point, if not an implementation for radiosity? Some examples of why this is so awesome.